There has long been interest in developing thermoplastic amorphous-semicrystalline blends that exhibit good mechanicals retention at high temperature and resistance to chemicals. Many polymer blends exhibiting crystalline properties are known in the art. However, these polymers generally tend to be incompatible with other polymers. When a compatible blend of a Polysulfone and another polymer is desired, it is often necessary to add a small amount of another ingredient or compatibilizer to promote more thorough blending between the two polymers. The additional ingredient may work by promoting bond formation between diverse polymer molecules. However, a compatibilizer that is effective in one system may not be effective in others; a great deal depends upon the specific functionalities of the molecules.
An important driving force in seeking new polymer blend is cost effectiveness. It is often desirable, for example, to discover new blends that have one or more desirable characteristics found in an expensive polymer, but cost less. This is usually accomplished by finding a suitable blend comprising the expensive polymer and a less expensive one.
Another reason for blending polymers is to create compositions that are better able to meet special needs than the polymer known in the art. Accordingly, it is sometimes desired to combine a Polysulfones with another polymer having special characteristics in the hope of creating a blend exhibiting the desired characteristics of both polymers. For example, polyphenylenesulfides (PPS) has very good thermal stability and chemical resistance, potentially important characteristics for a PPS blend. Polysulfones (PSU) exhibits good retention of mechanicals at high temperature. However, Polysulfone are generally incompatible with PPS. PSU/PPS blends tend to have large regions or domains of the individual polymers rather than fine, well-dispersed domains; the large domains tend to produce poor properties, e.g. parts having poor tensile properties.